Carbonization of carbonaceous materials



Patented Nov. 1933 UNITED STATES CARBONIZATION F CARBONACEOUS MATERIALS Harold J. Rose, Penn Township, Allegheny County, Pa., and William H. Hill, Arlingto N. J., assignors to The Koppel-s Company of Delaware, a corporation of Delaware.

Q No Drawing. Application May 3, 1930 Serial No. 449,638

Claims.

This invention relates to a process of treating coal and more particularly to the low-temperature carbonization of coal and other carbonaceous materials.

5 It is well known to coke coal by heating it in a liquid medium such as petroleum oil. The oils commonly in use are generally oils of high boiling points and are diflicult to remove from the coke produced therein. We have found that certain compounds may be used which are very easily removed from the coke.

The compounds selected have a high vapor pressure and incidentally develop relatively low pressures at their critical temperature. It is prefer-' able to use compounds that will not decompose at, and which have critical temperatures above, the carbonizing temperatures of the materials treated. For instance, the critical temperatures should preferably be above 450 C. or at least above 400 C.

The present process comprises heating carbonaceous substances in compounds preferably aromatic, such as naphthalene 'or diphenyl. Naphthalene, for instance, is perfectly stable at temperatures up to around 500 C. Its critical temperature is 468 C. The pressure developed at 468 C. by naphthalene is surprisingly low, namely, 39 atmospheres. This does not constitute a serious working obstacle.

The materials treated by our process may be such carbonaceous substances as lignites, brown coal, algal coals, cannel coals, sub-bituminous coals, bituminous coals, low volatile coals, oil shales, oil sands, asphalts, and organic waste materials such as saw dust.

We may carbonize coal for instance, in naphthalene at temperatures varying from about 250 C. to 460 C. depending on the kind of coal treated. In order to keep the naphthalene liquid at these temperatures it is necessary to carry on the process in a closed container, for instance, an autoclave.

The carbonization may be carried out in a continuous operation or in batches. In both cases it is advantageous to use the carbonizing liquid several times. In fact the liquid medium can be used so long as its tar content does not become too high.

It is further advantageous to avoid cooling the carbonizing liquid. For instance, the carboni-' zation may be conducted in a series of autoclaves, which are preferably rotating or are provided with stirrers, and after the carbonization is complete in one autoclave the liquid may be immediately 5 passed into a second autoclave which is charged with material to be treated. After the liquid is drained from the first autoclave, the temperature is usually high enough to vaporize most of the liquid which adheres to the solid carbonized matter.

The autoclaves may be connected with condensers and receivers for the recovery of the vaporized carbonizing medium. For the further removal of the carbonizing liquid from the carbonized matter, the latter may be heatedunder reduced pressures or it may be treated with steam.

The following examples are given by way of il1ustration:--

1. Equal parts by weight of bituminous or coking coal and naphthalene, which may be crude, are introduced into an autoclave provided with a stirrer. After closing the autoclave, it is heated to a temperature of 450 C. and is kept at that temperature for about one hour while stirring The autoclave is then cooled down preferably to a temperature below the boiling point of the crude naphthalene. The gases and vapors formed are condensed and the condensate mixed with additional naphthalene. The liquid and coke in the autoclave are separated by draining the liquid through screens. The coke is heated or steamed to drive off any adhering oily matter and the oils obtained in this way are mixed with additional carbonizing liquid.

2. A fluid mixture of equal parts by weight of coal and crude naphthalene is passed under pressure through heated pipes placed in a furnace. The flow of the mixture is regulated so that the coal is carbonized before leaving the furnace. The resulting mixture is distributed into tanks provided with filtering screens. The coke remains on the screens and the liquid passes through to be used again in the process. The coke is freed from adhering oil by heating it or by treating it with steam.

I Besides having the advantages inherent in carbonization processes in liquid mediaas, for instance, high heat conductivity and the absence of local overheating, our process has the advantage of utilizing a product, such as naphthalene for instance, which is available in large amounts and at a relatively low cost. The most important advantage, however, is the fact that our liquid media are very easily separated from a carbonized product on account of their high vapor pressures. Also, by the present process, large amounts of primary products are produced including gas and tars. The coke produced, is in a puffed state and has numerous gas cells distributed through it.

We claim as our invention: 1. A process of preparing coke from coal which process comprises heating a mixture of naphthalene and coal in a closed chamber to the carbon:

izing temperature of the coal but below the critical temperature of naphthalene, the proportion of naphthalene relative to the coal being such that there is suflicient of the naphthalene in the residue at the end of the carbonization that it may be drained or filtered off from the solid carbonized material, and separating the carbonized coal from the naphthalene and the tar formed in the process.

2. A process of preparing coke from coal which process comprises heating a mixture of naphthalene and coal in a closed chamber, agitating the mixture while heating, carbonizing the coal, the proportion of naphthalene relative to the coal being such that there is suflicient of the naphthalene in the residue at the end of the carbonization that it may be drained or filtered ofi from the solid carbonized material, filtering ofi the main body of the naphthalene and tar, and evaporating the adherent liquid from the carbonized coal.

3. A process comprising heating a mixture of liquid naphthalene and solid carbonizable material in a closed chamber, carbonizing the mixture, the proportion of naphthalene relative to the carbonizable material being such that there is sufficient of the naphthalene in the residue at the end of thecarbonization that it may be drained or filtered oil from the solid carbonized material, filtering off the main body of the naphthalene and tar, and evaporating the adhering liquid from the carbonized solid.

4. A process comprising heating a mixture of liquid naphthalene and solid carbonizable material in a closed chamber, carbonizing the said material, the proportion of naphthalene relative to the carbonizable matter being such that there is sufllcient of the naphthalene in the residue at the end of the carbonization that it may be drained or filtered off from the solid carbonized material, and separating the solid carbonized material from the naphthalene and tar formed in the process.

5. A process comprising carbonizing carbonizable material at a temperature below the critical temperature of naphthalene by heating a mixture of the carbonizable material and naph- 

